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The Vienna Convention

The Vienna Convention for the Protection of the Ozone Layer is a Multilateral Environmental Agreement. It was agreed upon at the Vienna Conference of 1985 and entered into force in 1988. In terms of universality, it is one of the most successful treaties of all time, having been ratified by 197 states (all United Nations members as well as the Holy See, Niue and the Cook Islands) as well as the European Union.

It acts as a framework for the international efforts to protect the ozone layer. However, it does not include legally binding reduction goals for the use of CFCs, the main chemical agents causing ozone depletion. These are laid out in the accompanying Montreal Protocol.

Ozone Layer

Life on Earth is possible because of the composition of our atmosphere. This atmosphere has evolved over geological time into a mixture to approximately
78.08% Nitrogen, 20.94% oxygen, 0.94% argon and 0.035% carbon dioxide. It also contains many other trace gases at concentrations ranging from parts per million to parts per trillion (1012). The biochemical, geochemical, and geophysical importance of these trace gases is much greater than their relatively low concentrations would suggest. This is particularly true of ozone and a number of trace gases (also known as source gases) which control the abundance of ozone and are responsible for greenhouse warming and predicted climate change.

Source Gases

Source gases are defined as those gases which influence levels of stratospheric ozone (O3) by transporting species containing halogen, hydrogen, and nitrogen to the stratosphere that are important in O3 destruction. Examples are the chlorofluorocarbons (CFCs) and methane (CH4 and nitrous oxide (N2O). Other source gases that also come under consideration in an atmospheric O3 concentration are those that are involved in O3 and hydroxyl (OH) radical chemistry of the troposphere. They are carbon monoxide (CO) and non-methane hydrocarbons (NMHC) in addition to methane.

Atmospheric ozone plays an important duel role in affecting climate. The stratospheric ozone layer surrounds the Earth like a shield and protects it from biologically-harmful ultraviolet radiation, yet lets through visible light to support the various life forms on Earth. O3 is also of primary importance in determining the thermal structure in the stratosphere. Most of the source gases, along with CO2 and water vapour (H2O), are climatically significant and thus affect stratospheric O3 levels by their influence on stratospheric temperatures.

Ozone is an important absorber of infrared radiation and is thus a greenhouse gas. Ozone is also toxic, and when formed near the Earth’s surface, affects human health, quality of air, vegetation, and food production.

Ultraviolet Radiation

The sun emits radiation over a broad range of wavelengths, to which the human eye responds in the region from approximately 400-700 nm. Wavelengths from 320-400 nm are known as UV-A; wavelengths from 280-320 nm are known as UV-B; and wavelengths from 200-280 nm are known as UV-C.

Ozone in the atmosphere absorbs virtually all UV-C and is expected to continue to do so under all foreseeable circumstances. On the other hand, UV-A is not absorbed at all by ozone. UV-B is partially absorbed by ozone.

The solar UV-B radiation has great natural variability and has been measured in a number of ways by ground-based techniques and more recently by instruments with high wavelengths resolution, providing spectral data. UV-B radiation has also been derived for a particular geographical location from ozone measurements in the absence of direct UV-B measurements.

A large increase in surface ultraviolet radiation has been observed in Antarctica during periods of low ozone.

Time line of Ozone Layer

1977: Coordinating Committee on Ozone Layer (CCOL) : In response to international concern about the ozone layer, the United Nations Environment Programme (UNEP) established in 1977 a Coordinating Committee on the Ozone Layer (CCOL) to review research and give forecasts of ozone layer depletion.

 1978: Action to Limit Emissions of CFC at National and Regional Level The United States banned ‘non-essential’ uses of CFCs such as aerosol propellants. Canada, Norway, and Sweden also banned non-essential uses of CFCs in aerosols.

 1980: The EC agreed to limit production of CFC-11 and CFC-12 and reduce their use in aerosols by 30 per cent.

1985: Vienna Convention for the Protocol of the Ozone Layer Following scientific assessments of the problem by UNEP, 49 countries met and agreed on the Vienna Convention for the Protection of the Ozone Layer. Although agreeing to the need for action, the countries failed at the time to agree on strategies. Some countries favoured a total ban on the non-essential use of chloro-fluorocarbons; others preferred to limit production.

1987: Montreal Protocol on Substances that Deplete the Ozone Layer In September 1987, a Protocol to the Vienna Convention was agreed upon. The Montreal Protocol on Substances that Deplete the Ozone Layer made provision for the control not only of CFCs but also of halons, and by the end of 1988, had been signed by over 40 countries and ratified by some 30 of them as well as the European Community.

The Protocol came into force on 1 January 1989. The condition that it had to be ratified by at least 11 countries representing at least two-thirds of global consumption of CFCs and halons in 1986 had been fulfilled the previous month. To date, 187 countries have ratified the Montreal Protocol.

The Protocol freezes production and consumption of five CFCs (CFCs, -11, -12, -113, -114, and -115) at 1986 levels by 1990, reduces them to 80 per cent of 1986 levels by 1994, and to 50 per cent of these levels by 1999.

Production and consumption of halons will be frozen at 1986 levels from 1992.

1987: The Antarctic Ozone Hole With the discovery of the ozone hole over Antarctica, it had become clear that the Protocol provisions were already inadequate. The ozone problem had proved to be more serious than was thought at the time that the Protocol was signed in 1987. Since then, a scientific consensus had developed that the newly-discovered ozone hole was caused mainly by CFCs and other anthropogenic ozone-depleting substances.

1989: Helsinki Declaration on the Protection of the Ozone Layer Consequently, international discussions began on the complete phasing-out of CFCs and other non-essential halons, and on restriction on other compounds containing chlorine. In May 1989, the parties to the Montreal Protocol which met in Helsinki made a declaration known as the ‘Helsinki Declaration on the Protection of Ozone Layer’ to phase out the production and consumption of CFCs as soon as possible and in any case no later than the year 2000; to phase out halons; to control and reduce ODSs; and to take various other steps to develop alternatives.

Amended Protocol
1990: London Conference The second meeting of the parties to the Montreal Protocol was held in June 1990 in London. This meeting produced an agreement to phase out CFC consumption completely in the developed countries by the year 2000 and in the developing countries by the year 2010. Also, the control substances were expanded to include methyl chloroform, carbon tetra chloride, and most fully halogenated CFCs.

While the Montreal Protocol on Substances that Deplete the Ozone Layer successfully phased out ozone-depleting substances (ODS) and put the ozone layer on the path to a full recovery, it led to a shift towards hydro fluorocarbons (HFCs). Like the ODS they replaced, HFCs are potent greenhouse gases that can be hundreds to thousands of times more potent than carbon dioxide (CO2) in contributing to climate change. Though they represent a small fraction of the current total of all greenhouse gases, their emissions are projected to increase nearly twentyfold in the coming decades, mostly due to increased demand for refrigeration and air conditioning, particularly in developing countries. If HFC growth continues on the current trajectory, the increase in HFC emissions is projected to offset much of the climate benefit achieved by phasing out ODS.

Amendment to Address HFCs under the Montreal Protocol

On October 15, 2016, with the United States’ leadership, 197 countries adopted an amendment to phase down HFCs under the Montreal Protocol in Kigali, Rwanda. Under the amendment, countries committed to cut the production and consumption of HFCs by more than 80 percent over the next 30 years. The ambitious phase down schedule will avoid more than 80 billion metric tons of carbon dioxide equivalent emissions by 2050—avoiding up to 0.5° Celsius warming by the end of the century—while continuing to protect the ozone layer. Under the amendment, developed countries will reduce HFC consumption beginning in 2019. Most developing countries will freeze consumption in 2024, with a small number of developing countries with unique circumstances freezing consumption in 2028. The plan also provides financing to certain countries, to help them transition to climate-friendly alternatives.

Key elements of the Kigali Amendment include:

  • Innovative and flexible structure;
  • Ambitious phasedown schedule;
  • Incentive for early action;
  • Broad participation;
  • Enforcement and accountability; and
  • Multiple opportunities to increase ambition.